C is for Chandrasekhar Limit

Stars die when they run out of enough energy to keep themselves puffed up like a balloon. Before that, pressure from fusion pushes against gravity and makes the star a certain size. Once fusion stops, that pressure isn't around any more and the star collapses--star death. Other stuff might happen, like a  type II supernova, but in the end, all you're left with is an ember of remaining material (a 'stellar remnant', but you can call it a star corpse if you are so inclined).

What happens to that material depends on how much mass there is. If you end up with a stellar remnant that's about the mass of our Sun, they call it a white dwarf star.  If you go bigger, there's enough gravity to create a neutron star. Go bigger than that, and there's so much gravity, it all collapses into a black hole. (Contrary to popular belief, a black hole isn't actually a hole. It's the most filled-up hole in existence, so dense is the matter within it.)

So, how much matter will remain as a white dwarf, and how much will become a neutron star?  The difference is called the Chandrasekhar Limit. (Named after an astrophysicist called Subrahmanyan Chandrasekhar, a Nobel prize winner who got routinely snubbed early on in his career despite his brilliance.)

Currently, we believe the Chandrasekhar Limit for a white dwarf is about 1.4 solar masses (nearly one-and-a-half times the size of our Sun), or about 2.765 × 10³⁰ kg.   That's about as big as they can get and still be called a white dwarf.

If the stellar remnant is under this mass, it'll be a white dwarf star. (Okay, white dwarves aren't really "stars", in that they don't glow under their own power. What you see is the heat radiating off it as it cools down into a cold cinder. There's an awful lot of heat, so this will take quite some time.) Electron degeneracy pressure is what keeps it from collapsing entirely on itself.

If the stellar remnant is over this mass, it collapses down into a neutron star, maintained at a radius of about 10 kilometers by neutron degeneracy pressure. But if you get enough mass to overcome neutron degeneracy pressure, the stellar remnant collapses so much it become a singularity, or a black hole. There, the gravity is so strong it will bend light.

So, a star dies and you end up with a white dwarf. The real fun with a Chandrasekhar Limit comes if the white dwarf is part of a binary system. If it's got a mate that's real close, and they swap spit exchange matter, there's gonna be fireworks.

A white star can only get as big as 1.4 solar masses. What happens if the white dwarf sucks off extra matter from its companion or two white dwarves merge?

It goes BOOM! When the matter of a white dwarf exceeds the Chandrasekhar Limit, you get a type Ia supernova.  This is where the star gets enough mass to ignite carbon fusion, and things go ker-splodey. In this case, the white dwarf is a goner.

Go hardcore: learn more about how the Chandrasekhar Limit affects White Dwarf stars.

What do you think a white dwarf will look like once it eventually cools?

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Her Grace has not yet had an opportunity for the direct observation of a white dwarf, but she'd like to get a gander at Sirius B.

B is for Baryonic Matter

Most of you are probably scratching your heads wondering what baryonic matter is, and its significance to astronomy.

Essentially, baryonic matter is all the matter we can see, taste, touch, and encounter. It is the atoms in our DNA, and the atoms in the stars. While the strict definition claims it is matter composed of baryons (like a proton or neutron, as opposed to photons or leptons), the loose definition (which is preferred by astronomers) is everything composed of atomic matter.

Yes, it's stuff.

This is significant to the astronomer, because it's most of what we observe. Baryonic matter tends to interact with the electromagnetic spectrum. Pretty much everything we know about the universe we know purely through observation. It's rare we send out probes and robots (like Opportunity on Mars) to physically sample stuff. Everything else we know came to us through observation of the interaction of BM with the EM.

Stars glow, and we can see their light in all manner of wavelengths. Other stuff can glow too, or it can reflect light, and we can observe that. Yet other stuff can block out or absorb light, and we can note it by the blank spot it creates (like a dust cloud).  Some galaxies are so massive they can bend gravity, and thus bend the light from even more distant galaxies behind them (through a process called gravitational lensing). We catch all this in light buckets called telescopes and then we study it and try to unravel the mystery of what we see.

You'd be surprised how well and specifically light and radio waves and X-rays interact with baryonic matter. Thus, we learn about our universe.

The opposite of baryonic matter is non-baryonic matter, or Dark Matter (so called because it doesn't emit any form of electromagnetic radiation that we can detect).  More about this on D-day.

Wanna go hardcore?  Here's some Astrophysics Data System articles to browse regarding Baryonic Matter.

What do you think is the most significant discovery regarding baryonic matter?

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Her Grace contains baryonic matter, as does the galaxy in which she lives.

A is for Astronomy and All Things in the Skies

Humans have always looked up to the skies and said, "That's cool. I wonder what's up there?" Myths and stories abound in every culture to explain the stars, the wandering stars (the Greeks called them "planets") and the mysterious dance of the Sun and the Moon. (Also, what's that big splotchy thing that looks like spilt milk?)

We're a naturally curious species. We like knowing as much as we can about everything about us. That includes the universe in which we reside.

Astronomy is the study of that universe we can observe.  Some consider astronomy the oldest of the natural sciences, starting with the measurement of time.

One of the really cool things about astronomy is that there is plenty of room for front-line work carried out by citizen scientists (like me). There is so much universe out there. From ground-based observations to data analysis from the many probes and other missions we send out there, there's plenty of work for the amateur astronomer. Comets, asteroids and even red dwarf stars are often discovered by citizen scientists.

But for the casual sky-watcher, there's plenty of fun to be had looking up with the naked eye. You don't need a fancy (expensive!) telescope to stargaze. Binoculars work fine, and there is nothing wrong with Mark-1 Eyeball observation.

The constellation Orion is currently visible in our night sky from most of the planet. At the very least, become familiar with it, for it is a magnificent example of many really lovely things astronomers like to study.

It looks like this:

The bright red star at the top left is Betelgeuse, the bright blue star at the bottom right is Rigel. Orion's belt is the three stars in the middle, and his 'sword', hanging from his belt, is actually a nebula. Orion is plastered against an outer arm of the Milky Way galaxy.

I hope you have a chance to observe it before it passes out of our night sky by May. We'll cover more regarding Orion when O drifts around.

Which constellation is your favourite?

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Her Grace has always loved astronomy and hopes you do too.

Thoughts on a Query

I am subscribed to Fussy Librarian and BookBub, both mailing lists that point me out to quality books currently on sale (or even free!).

Every few days I'll trawl through these lists to see if there's anything I want to add to my TBR pile.

As I read through the descriptions, some work for me, some don't. And then there's a third category where the description falls completely flat and uninspiring. These are usually for indie-published books. Even if the book is my crack, unless it's free on Kobo, if its description sucks, I won't get it.

A week ago I got a really nice, personal rejection from an agent for a novel I'm pitching. I'd convinced this agent to request pages based on a single Twitter line. (She said very nice things about my work, but in the end, wasn't quite for her.)  A few days ago I got three form rejections (to be added to the seventy previous form rejections I've received) for the same book, the one I'd pitched by a query letter.

These stats alone tell me that my query letter sucks.  While the book is stunning and beta-readers have raved about it, my query letter is letting it down.

Believe me, I've tried. I've done draft after draft of the query letter, workshopped it, minioned it, done everything I could think to make it a good query letter.  I've failed.

I've got about another hundred agents to go before I consider taking this book indie. If I can draft a really catchy query letter, I'll not have to consider indie. But if I can't, and an agent simply won't pick it up, indie might be the way to go, because great story.

Then I realised, the blurb on the back of the book, the one that readers of Fussy Librarian and BookBub look for is pretty much the same as the query pitch. If I can't entice an agent with my query letter, I won't be attracting readers with my description.

I dread having to rewrite my query letter Yet Again. I honestly don't know what I can do differently. But if I don't, I'm doomed to obscurity regardless of the publishing path I choose.

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Her Grace isn't always bad at all query letters. Just this one.

A to Z Challenge - Theme Reveal

This year for the A to Z Challenge, I will be posting about...

By career I am a novelist, but by education, I am an astronomer. As a practicing Citizen Scientist, I spend some time nearly every single day in study, analysis or observation of our universe.

The science of Astronomy is not to be confused with the practice of astrology (ie, predicting the future based on your horoscope).  Astronomy is a rigorous science involving physics, chemistry and biology (yes, really) to describe the universe we live in. For us, Mercury retrograde is nothing more than an apparent movement of a planet and not a portent of disaster in one's life, and our Zodiac has thirteen signs because the Sun spends a few days in Ophiuchus.

For the month of April, I intend to share a topic each day from Astronomy. Some things (like S is for Star) might be familiar, and others (C is for Chandrasekhar Limit) may be new to most people. I hope to present something for all levels of understanding, and welcome comments regarding what you think is cool about the universe.


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Her Grace is an ambidextrous polymath in pursuit of a MSci in Astronomy from Swinburne University.  And she is an author. To realise your place in the Universe, look to the heavens. To escape your place in the Universe, read her books.


Blog Posts:
A is for Astronomy and All Things in the Skies
B is for Baryonic Matter
C is for Chandrasekhar Limit
D is for Dark Matter
E is for Extremophile
F is for Fusion, or Why Stars Shine
G is for Galaxy
H is for Hydrogen and Helium, pretty much most of the matter of the universe.
I is for Infrared
J is for Jeans Mass and Jeans Length
K is for Kelvin, or how we measure temperature in the universe
L is for Lightyear
M is for Moon -and-  M is for Mars
N is for Nebula
O is for Orion
P is for Planet. It's okay, you can call Pluto a planet if you want.
Q is for Quasar
R is for Radio waves
S is for Star
T is for Telescope
U is for Ultra-violet
V is for Visible Spectrum
W is for Wobble
X is for X-ray.  Finally, an AtoZ blog entry where I don't have to stretch to find an entry.
Y is for Year
Z is for Zodiac

Get HER ENDEARING YOUNG CHARMS for free this week

It's
Read an Ebook Week
at Smashwords.

I'm rather fond of ebooks, for their convenience and pricing.  For the rest of this week (until Saturday), you can get an e-copy of HER ENDEARING YOUNG CHARMS for free from Smashwords by using the SFREE coupon at checkout.

I'm a big proponent of literacy, especially escapist fiction. If giving away my book for free this week helps someone, then it's a good week.

If you've already got your copy of HER ENDEARING YOUNG CHARMS, please share this info with someone else so they can get their hands on a great escapist novel.

If you do get a free copy, I ask that you kindly give it an honest review it at Amazon, Smashwords, GoodReads, or wherever you review novels. This helps other readers find good books.

____________________________
Her Grace is also getting other Smashwords novels for reading, despite her ever-growing TBR pile.

Tuesday's Tale - Preparation

We had prayed to the Goddess to bless us all, to inspire us in the defence of our town.  I had chosen the lady chapel in which to pour out my trepidation. I had taken much longer than the others in my devotion, for much fear shook my heart, It's hard to receive inspiration when overwhelmed with emotion.

Yet in the end I knew what I needed in my battle against the dragon--a longsword, a short sword, three knives, a crossbow and two bolts.

Two bolts, the Goddess inspired me. I pondered upon the significance of two bolts. One for each eye, perhaps, assuming this was a double-eyed dragon and not one of those with multiple heads.

No, I mused as I raided the castle armory. If it was one of those, swords would have been all but useless, as were axes or other cutting weapons. Remove one head, two more grew in its place.

So, single-headed dragon, possibly two eyes, land-based, or so I presumed. I had yet to see what the Goddess had inspired others to bring. Maybe it would be winged, and someone was inspired to bring nets. With these, they could bring the dragon down and me, with my sword, could kill it.

Maybe.

On my way to the stables, I passed the kitchen.

Elphine was there, making a sandwich.

I stopped. "What are you doing?" Packing lunch? Why? It wasn't as if we had time to stop to eat in the middle of battle.

She lifted her shoulders. "The Goddess inspired me thus."

I blinked.

Before I overcame my confusion, the belltower rang out its warning.

Dragon!

A shudder ran through the stones beneath our feet. A mighty roar echoed through the corridors. Elphine and I froze. Dread pooled in my stomach. A dragon, here? At the castle?  IN the castle?

Elphine slapped her sandwich together, stuffed it in her jerkin and ran after me.

We were almost to the stables when the rest of the Defendors came running back our way.  "Dragon IN the castle!" Tarrand called, terror making his voice break.

Sure enough, his footsteps were dogged by the hungry roars of a dragon in quick pursuit.

I got a glimpse of it before I could unfreeze my feet from fear.

It was one of the serpentine ones, long, and skinny, ideal for hunting its meals through the narrow stone corridors of our keeps. Now the short sword made sense.

Still, it was best we pick our battleground.  Down a long corridor, set up a defence in on open room, with enough space for all of us, but effectively pinning the dragon at the opening?  Attack its head at once with our swords while it hadn't room to manoeuvre?

Hard to think strategy when one is on the run.  Not enough breath to shout out one's inspiration.

Like frightened cows, we herded together, instead of separating to surround the beast.  Thus, we were easily shepherded down a corridor until we came to a locked door.

Of course! Not everyone was a fool in the castle. A locked door could easily thwart a dragon, just as it did us.

We pooled together in this dead end, our pleas of succor to the Goddess thickening the air.

Rathan went down first, when the dragon seized him by the leg and dragged him away, screaming. The dragon retreated quickly. Soon, Rathan's noise stopped, whether by distance, or the end of his mortal coil.

We went nowhere. We stopped and stared where the dragon once was. "Now what?" I asked. Then I shook my head. "We know what we're up against."  The others nodded, our sudden surprise ebbing away.

We didn't have much time left to strategise. Either the dragon would be back, or would set off to another part of the castle.  Either way, we needed a plan.

A quick inventory of our Goddess-inspired armaments revealed mostly short swords and daggers, a few ropes, and Elphine's sandwich (which she failed to mention to the others).  Our plan was simple: lasso the dragon, shoot it in the eyes with my crossbow bolts, hack at it until the head came away. Until we knew more about the dragon and its magic, this was the best plan for now.

The dragon could be anything. Who knew what it could do? It didn't breathe fire (that we'd seen). Could it shoot poison? Did it have mesmer skills like the cobra-tamers in the marketplace?  Who knew? I loaded my crossbow with the first bolt while the others fashioned slipknots for lassos.

No sooner did we come up with our plan, then the dragon returned. Why not? It had an entire feast holed up in a dead end.

Granted, this feast came armed.  As the dragon roared through, Tarrand and Lucine looped the lassos about its neck and pulled. I let loose with the bolt, right at its eye.  My hands shook so much, the bolt missed its target and bounced off the dragon's hide.

So that's what the second bolt was for.

Elphine ran in with a scream, to jab at the dragon's nose with her sword while I reloaded.

The dragon didn't like this. It hissed and roared, struggling against the ropes about its neck.

Alas, my second bolt also bounced off. I threw the crossbow away in frustration.  Why would the Goddess inspire me to bring a crossbow?  Perhaps for the same reason she inspired Elphine to bring a sandwich.

Indeed, it was down to me and Elphine to kill the dragon.  Tarrand and Lucine had their hands full with the dragon's ropes, pulling as hard as they could. It didn't seem their efforts to choke the dragon were succeeding, but at least they kept it immobile. It couldn't get away, and it couldn't move.

We went in with swords, stabbing at its eyes, its nose, anywhere that the armour of its scale didn't cause our swords to bounce off.  That wasn't much. Every time we went for an eye, the dragon would blink, thus protecting that orb.  The nose, likewise, had the same sort of strange closing, to keep anything foreign out of its nostrils.

The mouth, with its many needled teeth, was not as vulnerable as we had hoped. It had clamped down on Elphine's sword, thus wrenching it from her hands. She retreated away while I drove at it once more, although my attacks were useless.

My heart thumped. Surely I was not the last defence this castle had against this dragon?  I stabbed again and again, uselessly, until my arms ached with effort.  I pulled back to Elphine, more from exhaustion, than anything else. My second intention, after gaining a rest, was to give Elphine a second sword.

Instead, she pulled out her sandwich, more in awe, than in hunger. She peeled it apart.

Armed with only this, she ran toward the dragon.

It pulled back, but only so far, due to the ropes. Elphine reached out and smeared the sandwich across the dragon's eyelids, then retreated.  I guess when all you've got left is a sandwich, you fight with what you've got.

I had a sword ready for her when she returned.  We braced for the dragon, but it never came forth.

Instead, the dragon blinked and blinked. It attempted to scrape its head against the walls to remove the sandwich. One piece of bread stuck to its eyelid, refusing to be dislodged.

"What kind of sandwich is that?" I breathed.

"Peanut butter," Elphine replied, still in awe.  She doesn't like peanut butter.

Neither did the dragon, apparently. Its roars changed to whines as it fought the ropes. It could not reach a claw around to scrape away the sandwich. Neither could it rub it off on the walls. We watched as its eyes swelled shut and its breathing grew laboured.

I had my sword ready, hoping for an opportunity to move in and finish the job, but Elphine stood in awe. "Is it... allergic?"

I eased my stance. As we watched, the dragon's face swelled, causing the scales to expand, opening its armor and giving us targets to stab for.

We did not wait but ran forth to slip our swords between the scales.

The dragon whimpered and thrashed its head. Eventually it slowed, more from its laboured breathing, rather than our pinpricks.  Tarrand and Lucine kept hold of the ropes, despite their exhaustion. Elphine and I helped them, for there wasn't much more we needed to do than watch the thing die from the shock of a peanut butter sandwich.

Later, we cut off its swollen head just in case.

While the castle servants came to drag the corpse away, we returned to the chapel to give thanks to the Goddess in all her wisdom, for inspiring Elphine.

I still think about the crossbow bolts.